Method for attaching a plastic cover and apparatus employing same

ABSTRACT

A method and apparatus employing the method are disclosed for attaching a plastic cover to a safety belt retractor frame. A plastic cover having a pair of spaced legs is attached to a seat belt retractor frame by inserting the legs through an opening in the retractor frame and wedging a plastic plug between the legs to hold them tightly in the opening and restrict withdrawal from the opening.

The present invention relates generally to safety belt retractors andmore particularly to the method and means for attaching plastic coversto safety belt retractor frames.

Safety belt retractors usually include a main carriage or frame uponwhich the safety belt winding reel and associated mechanisms aremounted. The retractor frame usually has a base plate with upstandingside plates. The reel is mounted between the side plates, and apparatusor mechanisms associated with the reel, such as coil rewind springs ortension locks, are mounted on the outside of the side plates and engagethe end of the reel that extends through the side plate. Compare, forexample, U.S. Pat. No. 3,869,098, which illustrates a typical safetybelt retractor frame, with the belt reel mounted between side plates andwith a winding prevention mechanism secured on the outside of the sideplate.

The various reel-associated mechanisms are usually enclosed by shallowplastic cups or caps which are attached to the retractor frame. Thesecovers serve not only to protect against dust or dirt, but often theyare actually attached to or engaged against the mechanism enclosed andare an important part of the operation of the device. For example, insome retractors, the tension lock or retractor control mechanism isactually mounted on a center spindle inside the cover. The cover ismounted on the side plate of the retractor and the belt reel extendsthrough the plate to engage the winding control mechanism. U.S. Pat. No.3,861,696 illustrates this construction. A coil spring for rewinding thebelt reel may also be enclosed in the plastic cover, with the coverserving as a stationary connection for one end of the spring, the otherend being attached to the belt reel. In both cases, if the cover is notsecurely attached to the retractor frame or accidentally releases fromthe frame the safety belt will not function properly. If a tension lockfails because the cap or cover disengages from the side plate of theretractor frame, the safety belt will continually, and uncomfortably,exert a pulling force against the passenger. If a rewind spring isenclosed, failure of the cover may prevent the safety belt fromrewinding properly. Equally important, failure of a cover over a rewindspring may permit the spring to fly off the belt reel, presenting ahazard to persons nearby. This problem is more prevalent in assembly,installation or repair of safety belt retractors when workmen areexposed.

Accordingly, for safety belt retractors to work properly and safely, theplastic covers must be securely attached to the retractor frames. In thepast, some plastic covers have utilized a "snap-in" action, with spacedresilient legs which are inserted through openings in the retractorframe. The resilient legs include radial shoulders with sloped sideswhich cause the legs to compress together as they are inserted throughthe openings. After the shoulders are beyond the inside edge of the sideplate the resilient legs spring apart and the shoulders hook over theedge of the opening to restrict withdrawal of the legs and thereby holdthe cover in place. However, because the legs are resilient and may flexsufficiently to permit the shoulders to disengage when force is appliedto the cover, this kind of simple snap-in attachment has provenunsatisfactory.

Hot swaging the ends of the plastic legs after they have been insertedthrough the frame has also been tried. Although the cover is held moresecurely in place than in the snap-in arrangement, the swaging operationis manual, adding to product cost, and plastic builds up on the swagingtool after repeated use, eventually requiring cleaning and possiblypreventing the tool from being used in narrow spaces in the retractorframe. Rivets have also been used to attach covers to retractor frames.But this requires additional operations as well as materials and thusincreases the cost.

Accordingly, it is an object of the present invention to provide anefficient and low cost method and apparatus for securely attachingplastic covers to retractor frames.

It is further object of the present invention to provide method andapparatus for attaching plastic covers to retractor frames without theneed for additional parts or manual operations.

These objects are met by the present invention by providing a method andapparatus for inserting and locking spaced resilient legs of a plasticcover in openings in a retractor frame. The legs may include shouldersor other means for gripping or abutting the frame. After the legs areinserted, a plastic plug is wedged between the legs to prevent the legsfrom disengaging from the frame and thereby preventing accidentalrelease of the cover. Preferably, a staking pin is used to punch out aplastic plug from the cover portion behind the legs and to press theplug to between the legs in one direct motion, wedging the legs apartand preventing flexing of the legs and consequent disengagement of theshoulders from the frame.

These and other objects of the invention are disclosed in the followingdetailed description and the attached drawings, of which,

FIG. 1 is a perspective view of a plastic cover enclosing a tension lockdevice which is to be attached to a retractor frame.

FIG. 2 is an enlarged view of the spaced attaching legs of the covertaken along line 2--2 of FIG. 1.

FIG. 3 is a perspective view of a safety belt retractor frame with anattached side cover embodying the present invention.

FIG. 4 is a sectional view taken along lines 4--4 of FIG. 3.

FIG. 5 is a side view taken along line 5--5 of FIG. 4.

FIG. 6 is a plan view, partially in section, of a machine embodying thepresent invention for attaching plastic covers to retractor frames.

FIG. 7 is an enlarged view taken along line 7--7 of FIG. 6.

FIG. 8 is a partial left side view of the machine illustrated in FIG. 6.

FIG. 9 is a perspective view, partially in section of the machineillustrated in FIG. 6.

FIG. 10 is a front view of a die used in the machine embodying thepresent invention.

FIG. 11 is a plan view of the die shown in FIG. 10.

The present invention is generally embodied in a safety belt retractor10 and in the method and machinery for manufacturing the same. Theretractor includes a frame or carriage generally at 12, with anupstanding side plate 14 on each side of a safety belt retractor reel16. The retractor reel extends through the side plates to engagemechanisms, such as a tension lock device 18 shown in FIG. 1. Thesemechanisms are enclosed by a shallow plastic cap or cover 20 which aremounted against the side plate of the retractor frame.

In accordance with the present invention, the cover 20 is simply, butsecurely and permanently, attached to the side plate 14 of the retractorframe 12 by inserting flexible spaced legs 22 through openings 24 in theretractor frame and wedging a plastic plug 26 between the legs to holdthe legs apart and to prevent disengagement of shoulders 28 on the legsfrom the inside of the side plate. The plastic plug may be formed andinserted between the spaced legs by punching out a portion of a radialring 30 behind the spaced legs and forcing it to between the legs. Thisis most easily accomplished with a machine such as that illustrated inFIGS. 6 et seq. The cover is deposited in the upper end of a die 32,which is spaced below a holding frame, generally at 34, for holding theretractor frame in stationary position. Staking pins 36 extend throughthe die from beneath the radial flange of the cover to below theopposite end of the die. After the cover is deposited into the die withthe radial flange overlying the staking pins at the location of thespaced legs 22, the retractor frame is inserted into the holding frameabove the die, with a side plate facing down. A ram 38 may then beactivated to drive the die toward the retractor frame, pushing thespaced fingers of the cover into the openings in the side plate. The ramalso engages the staking pins which extend to below the die, forcing thestaking pins upward through the radial flange and driving a plug portionof the flange to between the spaced legs. This plug, wedged between thelegs, prevents flexing of the legs and holds them tightly within theopenings in the side plate.

Turning now to a more detailed description of the present invention,which is shown in its preferred embodiment for illustration only, theretractor frame 12 is the main structural member of the safety beltretractor. It is generally of one-piece metallic construction ofsufficient strength to resist the acceleration and vibration forceswhich may be applied against the safety belt system. The frame is formedby bending the side plates 14 upwardly along the side edges of a baseplate portion 40. One end of the retractor frame includes means (notshown) for attaching the frame to a structural member of the vehicle inwhich it is utilized. At the other end, the safety belt reel 16 ismounted between the side plates and securely attached to them, usuallyby a central axle which extends through openings in the plates. (notshown) Several small openings 24 are drilled or stamped into the sideplate around the axle for attachment of the cover 20 over the end of theaxle. The position of the openings corresponds to the location of thepairs of spaced legs 22 on the cover which is to be attached.

Any selected mechanism, such as the tension lock device 18 or aretractor spring, or none at all, may be attached to the end of the beltreel axle. The tension lock device illustrated in FIG. 1 relieves thepassenger from constant belt pull after the belt is adjusted. Thetension lock is mounted on a central, recessed spindle (not shown)extending from the inside of the cover. Central slots 42 in the tensionlock are designed to engage over a mating end of the reel axle.

The cover 20 which surrounds the tension lock is a shallow cup or cap,with a flat bottom wall 44 and a continuous side wall 46 extendingperpendicularly from the edge of the bottom wall. The illustrated coveris generally circular except for an irregular portion (best seen in FIG.3) formed by flat side walls intersecting to form a angular extension.The radial flange 30 extends perpendicularly from the edge of the sidewall along the circular portion of the cover but not the irregularportion.

For attaching the cover 20 to the side plate 14 of the retractor frame12, pairs of spaced legs 22 extend upwardly from the radial flange 30 atselected intervals therealong. At the locations of the spaced legs theradial flange is wider to permit proper spacing of the legs from theside wall. Preferably, the entire cover, including the bottom wall 44,side wall 46, radial flange and spaced legs are of one-piece, moldedplastic construction. Although a variety of plastics sufficientlystrong, resilient, easy to mold and relatively inexpensive may be used,nylon is the preferred material.

Each leg 22 is back-to-back with a substantially identical leg to forman adjacent pair of legs, and a description of one leg or one pairapplies equally to all other legs and all pairs. Each leg of a pair hasa generally flat back-to-back facing surface 48 with a curved frontsurface 50 facing away from the paired leg. The legs taper from agenerally semi-circular cross-sectional shape at the radial flange 30 toa smaller end. As may be seen in FIGS. 2 and 4, this creates a V-shapedspace or notch between the legs of each pair. To hook over the insideedge of the openings 24 in the side plate 14 and thereby restrictwithdrawal of the legs from the openings, the radially extendingshoulder 28, defined by a surface perpendicular to curved front surface50, is provided on each leg between the flange 30 and the end of theleg. The shoulder must be spaced from the flange a distance at leastequal the thickness of the retractor frame. Otherwise the legs could notbe inserted far enough through the opening for the shoulder to overlapthe inside edge.

Each pair of legs may also be described, somewhat differently, as asingle upstanding cylindrical insertion post with a pair of oppositelyfacing shoulders near the end and a V-shaped notch between theshoulders, dividing the insert into a spaced pair of identical legs,facing back-to-back.

To guide each pair of legs 22 into the selected opening 24 in the sidewall 14, an outside facing cam surface 52 extends between the edge ofthe shoulder 28 and the free end of the leg. The cam surface serves toengage the edge of the opening 24 as the legs are pushed thereagainst,thereby guiding the legs into the opening and simultaneously squeezingeach pair of legs together for insertion therethrough. In other words,as each pair of legs is pushed into an opening in the retractor frame,the cam surface slides across the edge of the opening, forcing the legstogether until they are sufficiently close to be inserted through theopening. After the shoulder 28 passes the inside edge of the retractorframe the resilient legs spring apart with the shoulder hooking over theedge of the frame.

The resilience of the legs 22 is due in large part to the plasticconstruction, preferably nylon, of which the entire cover 20 isconstructed. However, because of the resilience of the nylon legs, theymay flex when various forces are applied against the cover and permitthe shoulders 28 to disengage from the side plate 14. To lock the legs22 in a spaced relationship and to prevent flexing of the legssufficient for the shoulders to disengage from the edge of the retractorframe, the plastic plug 26 is formed and then wedged tightly between thelegs. The plug may be formed as an entirely separate step from othermaterials and then inserted and wedged between the legs. As more clearlyseen in FIGS. 4 and 5, the plug is preferably, and most conveniently,formed and inserted by driving a portion of the radial flange 30 frombehind the legs directly to a location between the legs within theopening in the retractor frame side plate. In this manner a plug havinga length equal to the thickness of the radial flange, less the amountcompressed, is wedged between the legs. The plug should be sufficientlythick to wedge tightly between the legs but not so thick as to weakenthe flange or the legs when punched from the flange to between the legs.In the preferred embodiment the staking pin which is used to drive aplug from the flange to between a pair of legs has a tapered end about0.065 inches in average diameter. The legs between which the plug isinserted have a base, semicircular diameter of about 0.125 inches. Theplug is preferably driven to a position substantially within the openingin the side plate of the retractor frame. As illustrated, the plug maybe positioned completely within the opening between the edges of theside plate.

Apparatus for attaching the cover 20 to the side plate 14 of the safetybelt frame 12 is illustrated in detail in FIGS. 6 through 11. Briefly,the holding frame 34 serves to lock the retractor frame 12 in astationary position, with the side plate to which the cover is to beattached facing downward. The cover is nested in the top end of the die32 below the holding frame, with the spaced legs 22 pointed upwardly inregistration with the openings 24 in the side plate. Staking pins 36extend through the die from just below the radial flange 30 of the coverto beyond the bottom of the die. The top end of each pin is positionedbelow one of the pairs of spaced legs 22. The other ends of the die andstaking pins rest atop the ram 38. When the ram is driven upwardly, thedie forces the spaced legs of the cover through the openings in the sideplate and the ram drives the staking pins through the flange to force orpunch a plug portion of the flange to a position between the legs,thereby holding the legs apart and preventing disengagement of theshoulders 28. Thus the cover is securely attached in one simple machineoperation, with a minimum of complicated machinery or procedures.

The holding frame, generally at 34, is mounted in a flat, rectangularmachine surface 54 which has a center bore 55 sufficiently large for theinsertion of the die 32 from therebelow. The holding frame is adapted tolock the retractor frame in a stationary position over the center bore.The holding frame includes a pair of spaced, parallel L-shaped channels56 attached directly on the top of the machine surface and on each sideof the center bore. The channels are facing to provide slidewayssurfaces 58 along which the retractor frame may move.

To stop the retractor frame at a location in proper alignment with thecenter bore 55, the holding frame includes a stop 60 extending betweenthe channels 56 on one side of the center bore. The stop is preferablyof two-part construction -- a lower plate 62 with a recessed curvilinearfront edge and a U-shaped upper plate 64 which are attached together byscrews 66 (FIG. 7). The lower plate extends fully between the parallelchannels 56 and rests on the slideway surfaces 58.

As noted earlier, the retractor frame 12 is slid along the channels 56with the side plate 14 facing down. FIGS. 6-8 illustrate the retractorframe in phantom and the phantom arrow indicates the insertion of theretractor frame into the holding frame. The base plate portion 40 of theframe is preferably to the rear, (FIGS. 6-8), and the stop 60 is locatedso that it abuts the leading edge of the downward facing side plate whenthe plate is properly aligned with the center bore 55 in the machinesurface 54. But in addition to acting as an alignment device, the stop60 also acts to hold the retractor frame against vertical and horizontalmovement. The front edge of the lower plate 62 of the two-part stop isrecessed from the front edge of the top plate 64. So, when the retractorframe is slid along the channels to abut the stop, the leading edge ofthe downward facing side plate extends under the top plate of the stop,which acts as a holddown or clamp against vertical movement of theretractor frame. Horizontal restraint on the retractor frame is providedby a rear leg 68 of the top plate of the stop. The leg 68 is spaced fromthe inside of the channel 56, and when the retractor frame is slid intoplace, the base plate portion 40 of the retractor frame is insertedbetween the rear leg and the channel (FIG. 8).

The holding frame 34 provides additional vertical restraint on theretractor frame by providing a holddown along the top of the frame. Morespecifically, rectangular backplate 70 extends vertically from themachine surface 54 along the outside of one of the channels 56. A coverplate 72 is attached to the upper edge of the backplate by a pair ofscrews 74 and extends outwardly, over the bottom channels. A front plate76 depends for a short distance from the front edge of the top plate,and is attached to the top plate by screws 78. To hold the retractorframe down, an L-shaped channel 80 is secured at the inside junctionbetween the top plate and the backplate. The channel 80 is parallel tothe bottom channels 56 and positioned to slidably engage the retractorframe at the corner between the upward facing side plate 14 and the baseplate 40. A rectangular bar 82 at the corner between the top plate 72and the front plate 76 also provides a slideway, parallel to thechannels 56 and 80, over the top of the upperward facing side plate,thereby holding the retractor frame against upward movement.

The operation of the holding frame is thus relatively clear. Theretractor frame 12, with the selected side plate 14 facing downward, isplaced upon the bottom channels 56 which extend out from under the coverplate 72. The retractor is then slid along the channels, beneath thecover plate, where the channel 80 and bar 82 slidably engage over theupward facing side plate, until the frame abuts the stop 60, whichindicates that it is in position, properly aligned with the center bore55 in the machine surface 54. In this position, vertical movement of theretractor frame is prevented by the stop which overhangs the leadingedge of the side plate and by the channel 80 and bar 60 which areengaged against the upward facing side plate to provide a holddown. Andhorizontal movement in one direction is restricted by the insertion ofthe leading edge of the base portion 40 of the retractor frame betweenthe rear leg 68 of the stop and the channel 56.

To attach the cover 20 to the downward facing side plate, the die 32 ismounted within the center bore 55 in the machine surface. The die is ofgenerally cylindrical construction with a cylindrical base portion 84and a narrower cylindrical upper portion 86. The die is preferablymetallic but may be fabricated of any other material of sufficientstrength. The upper surface of the die is recessed, as by machining ormolding, to conform to the shape of the cover which is to be depositedtherein. In the present embodiment, the recess is shallow, cup shapedwith an irregular angular portion. (See FIG. 11). Preferably, the recessin the die only receives the bottom and side walls of the cup, and theradial flange overlaps the top surface of the die. (FIG. 10). The lowerend of the die is centrally bored to receive a coil spring 90.

For inserting the staking pins 36, the die 32 is drilled completelybetween the upper surfaces 88 and the bottom surface 92. The spacing andnumber of drillings corresponds to the spacing and number of pairs ofspaced legs 22 in the cover 20. Because the shape of the cover isirregular and the recess in the end of the die corresponds to the covershape, the cover and the spaced legs are always in the same predictableposition when inserted into the die. Accordingly, the die is drilled ateach location of the spaced legs for insertion of a staking pin. With acover like that illustrated in FIG. 1 with three pair of attaching legspaces around the flange 30, the die is drilled for three staking pinsto extend to just below the spaced legs. The numeral 93 indicates thedrill holes in FIGS. 9-11. The staking pin hole is drilled larger in thelower portion of the die for insertion of a coil spring 94 around thestaking pin.

Turning to the staking pins themselves, each staking pin 36 is long,metallic and generally cylindrical in shape. A wider cylindrical base 96is attached to one end of the pin and slightly tapered punch portion 98is provided at the other end. The punch portion is sufficiently long toextend substantially through the radial flange 30 of the cover 20 andsufficiently thick to punch out a portion of the flange that will wedgetightly between the legs 22. In the preferred embodiment, the punchportion has a diameter of about 0.065 inches for punching plug totightly wedge between spaced legs having an overall diameter of about0.125 inches. Overall, the staking pin is longer than the die by aselected amount at least equal to the thickness of the radial flange ofthe cover.

The staking pins are inserted into die 32 from the bottom. Before theyare inserted, the coil spring 94 is placed over the pin, resting uponthe cylindrical base 96. The portion of the staking pin hole with alarger diameter for insertion of the coil spring is shorter than thespring, thus putting the spring under compression when the pin isinserted.

The die 32 and staking pins 36 rest atop the ram 38. The ram isgenerally a flat disc with a center, downward extending shank 100attached in the usual manner to a hydraulic cylinder 102 therebelow. Thehydraulic cylinder is rigidly held in place by a bracket 104 which isbolted to the underside of the machine surface 54. Guide pins 106 extendthrough the ram and are attached below the machine surface 54. Largeheads 108 on the guide pins prevent the ram from retracting too far anddislodging the die from the center bore 55 in the machine surface orpermitting the staking pins to fall from the die.

The ram 38 is generally horizontal with a flat upper surface upon whichthe die and staking pins rest. The die is actually supported above thesurface of the ram by the large coil spring 90 which extends into thecenter bore in the lower end of the die. The spring keeps the die in aslightly raised position in the center bore 55 of the machine surfaceeven when the ram is retracted. The coil spring 94 around the stakingpin, which is in compression, keeps the cylindrical base 96 of the pinin actual contact with the top surface of the ram.

With this construction, when a cover is nested in the upper end of thedie, and a retractor frame is properly positioned in the holding frame,the cover may be simply and quickly attached to the retractor frame byactivating the hydraulic cylinder 102.

The cylinder drives the ram upwardly, forcing the die and cover againstside plate of the retractor frame, and the spaced legs 22 of the coverinto openings 24 in the side plate. The length of the ram stroke must atleast be sufficient to drive the legs far enough into the openings forthe shoulders 28 to hook over the inside edge of the frame. The ram alsoengages the cylindrical bases 96 of the staking pins, forcing the pinsupwardly through the radial flange 30 to punch a plastic plug from theflange to between the spaced legs.

The distance the staking pins 36 are driven through the radial flange 30is a function of the amount by which the length of the staking pinsexceeds the length of the die 32. The drilled staking pin holes 93 inthe die are large enough for the base 96 of each staking pin to bepushed thereinto upon the upward stroke of the ram 38. Thus, when theram impacts the bottom surface 92 (also called impact surface) of thedie, the staking pin is driven through the die and the radial flange byan amount equal to the difference between the length of the pin and thedie. This distance, which is also approximately equal to the length ofthe punch portion 98 of the staking pin, must be determined so that theplug 26 is wedged tightly between the legs. This will depend on thethickness of the radial flange 30 and the size of the legs in theparticular cover.

The actual operational sequence may vary. If the coil spring 90 isstrong and stiff, sufficient force may be exerted against the die tocause insertion of the spaced legs 22 into the opening 24 in the sideplate 14 before the ram moves toward the die far enough to drive thestaking pins into the radial flange 30. The spring stiffness requiredfor this sequence depends on the resistance of the legs to insertion inthe openings, which is a function of the slope of the cam surface 52 onthe legs and the resilience of the legs. If the spring is stiff enoughto easily overcome these cumulative resistant forces, the legs willlikely be snapped into the openings in the side plate before the stakingpins are driven into the flange 30.

If the spring 90 is not sufficiently strong, the staking pins 36 mayengage the radial flange 30 before the spaced legs 22 are completelyinserted into the openings 24 in the side plate. In this case, thestaking pins, alone or in combination with the die 32, drive the legsthrough the openings. However, either mode of operation described aboveis satisfactory so long as the staking pins do not drive the plugportion 26 from the radial flange before the legs are insertedsubstantially into the openings.

The apparatus described above may be operated automatically or manually.The cover 20 is first deposited into the upper end of the die 32,nesting in the matching recess. A retractor frame 12 is then slid into aholding frame above the die. The die and holding frame are positioned sothat the spaced legs 22 of the cover are in registration with openings24 in the side plate 14 of the retractor frame. The operator thenactivates the hydraulically-operated ram 38 which drives the die towardthe side plate, inserting the legs into the openings at least until theshoulders 28 hook over the inside edges. The ram also drives stakingpins through the radial flange of the cover to force plug portion of thecover to positions between the legs, preventing them from flexing andaccidentally permitting the shoulder to disengage.

The hydraulic ram may then be retracted, and the retractor frame with apermanently attached cover may be removed.

In summary, the present invention presents a unique method and apparatusfor attaching plastic covers to safety belt retractor frames. Spacedlegs on the cover are inserted into an opening in the frame, a plasticplug is formed and inserted between the legs to wedge them tightlyapart. When the legs are carried on a flange, the plug may be mostlyconveniently formed and inserted by punching it from the flange behindthe legs to directly between the legs.

Apparatus employing the invention utilizes a die in which the cover isfirst deposited, the safety belt retractor frame is then slid into aholding frame above the die to hold the retractor frame in a stationaryposition. A ram drives the die against the retractor frame insertingspaced legs from the cover into openings in the frame. The die may alsoinclude staking pins, which are driven by the same ram through theradial flange, thereby punching a portion of the flange to between thelegs and wedging them apart within the opening.

The preferred embodiment present invention has been described forillustration only. It is not intended to disclaim the use of equivalentsteps or apparatus, some may be obvious immediately and others onlyafter study.

Various of the features of the invention are set forth in the followingclaims.

We claim:
 1. A method for permanently attaching a plastic cover having aplurality of interlocking means each having at least a pair of spacedlegs to a device having openings each for receiving said legs of anassociated interlocking means, said method comprising aligning theplurality of pairs of spaced legs each with one of said openings,simultaneously inserting each one of said pair of said legs into one ofsaid openings, simultaneously forming plastic plugs by punching out anintegral portion of said cover at each location between a pair of saidlegs and simultaneously inserting each of said plugs between said legsto hold them tightly and permanently in said openings.
 2. A method inaccordance with claim 1 in which the steps of inserting the plugincludes forcing the punched-out plug in an axial direction from thehole formed thereby in said cover.
 3. A method for permanently attachinga plastic cover having a flange with at least one pair of spacedresilient legs extending therefrom at several spaced locations aboutsaid flange to a safety belt retractor frame having openings forreceiving said legs, said legs including gripping means to engage saidframe to restrict withdrawal of said legs from said opening, said methodcomprising aligning the spaced legs at said several locations with anassociated opening, simultaneously inserting said legs into said openingat least until said gripping means engages said frame and punching aplastic plug directly from said flange at each of said locations,inserting each of said plastic plugs between said legs; said plugsthereby holding said legs apart and preventing flexing of said legs anddisengagement of said gripping means and removing of said cover.
 4. Amethod in accordance with claim 3 in which said plastic plug is punchedto a position substantially in said opening.
 5. A method for attaching aplastic cover having a flange with at least one pair of spaced resilientlegs extending therefrom to a safety belt retractor frame having anopening for receiving said legs, said legs including gripping means toengage said frame to restrict withdrawal of said legs from said opening,said method comprising inserting said legs into said opening at leastuntil said gripping means engages said frame and punching a plastic plugdirectly from said flange to between said legs; said plugs therebyholding said legs apart and preventing flexing of said legs anddisengagement of said gripping means, said cover being supported in adie with said spaced legs extending toward said retractor frame and inregistration with said opening, said legs being inserted into saidopening by driving said die and retractor frame together, and saidplastic plug being punched by driving a staking pin through said flange.6. A method in accordance with claim 5 in which said die includes animpact surface facing away from said retractor frame and said stakingpins are cooperatively associated with said die and extend from adjacentsaid flange at said spaced legs to a selected distance beyond saidimpact surface, said die and retractor frame are driven together byholding said retractor frame stationary and driving a ram against saidimpact surface of said die thereby forcing said die against saidretractor frame, said ram also engaging said staking pin to drive itthrough said radial flange said selected distance.
 7. A method forattaching a plastic cover to a safety belt retractor frame, said coverhaving a generally shallow cup shape with a flange extending radiallyfrom the open edge of the cup and a plurality of spaced pairs ofresilient legs with gripping shoulders extending from the flange, saidretractor frame having a plurality of openings each opening beingadopted to receive one pair of spaced legs, said method of attachmentcomprising:inserting said retractor frame into a holding frame forholding said retractor frame in a stationary position; depositing saidcover into a die having opening means in one end with a shallow cupshape to receive said cover with said legs extending toward saidretractor frame in registration with the openings in said retractorframe, said die further including bores for receiving staking pins toadjacent said radial flange of said cover at said spaced legs, saidstaking pins extending through said die to a selected distance beyond animpact surface at the other end of said die facing away from saidretractor frame; driving a ram against said impact surface of said die,a spring means being disposed between said ram and said die so that saiddie is first driven to insert the spaced legs of said cover into theopenings in said retractor frame at least until said shoulders engagesaid retractor frame, continuing motion of said ram to said impactsurface serving to drive said staking pins through said radial flange bysaid selected distance to punch a portion of said flange to between saidlegs to prevent flexing of said legs and disengagement of saidshoulders.
 8. An apparatus for attaching a plastic cover having at leasta pair of spaced legs to a safety belt retractor frame having an openingfor receiving said legs, said apparatus comprising holding means forholding said retractor frame, support means adjacent said holding meansfor supporting said plastic cover with said legs in registration withsaid opening in said retractor frame, driving means cooperativelyassociated with said holding and support means for driving said holdingand support means together to insert said legs into said opening andpunch means cooperable with said support means for punching a plasticplug from said cover and inserting it between said legs to hold saidlegs tightly in said opening.
 9. An apparatus in accordance with claim 8in which said punching means is engageable by said driving means topunch out said plug when said driving means moves said holding andsupport means together.
 10. An apparatus in accordance with claim 9 inwhich said support means is a die with a first end facing said holdingmeans and shaped to receive said cover and a second end facing away fromsaid retractor frame for impact with said driving means, said punchingmeans comprising a staking pin extending through said die from adjacentsaid pair of spaced legs of said cover at said first end to beyond saidsecond, impact end, and said driving means comprising a ram drivableagainst the impact end of said die to force the legs of said cover intosaid opening and to engage the staking pins to punch a portion ofplastic from the cover to between said legs to hold them tightly in saidopening.
 11. An apparatus in accordance with claim 10 in which saidholding means is a holding frame with outwardly extending sliding railsfor sliding said retractor frame into proper position within the holdingframe and an overhanging lip at the end of said rails to engage over theedge of said retractor frame to hold it stationary.
 12. An apparatus forattaching a plastic cover of generally shallow cup shape with a radialflange and a plurality of pairs of spaced resilient legs extending fromthe flange to a safety belt retractor frame having at least one sideplate with a plurality of openings, each opening adopted for receivingone of said pairs of legs, said machine comprising a holding frame forholding said retractor frame in a stationary position, a die associatedwith said holding frame and movable into a position closely adjacentsaid side plate, said die having a first end facing said side plate,said first end being recessed for receiving said cover with said spacedlegs in registration with said openings in said side plate, said diealso having a second end facing away from said first end, a plurality ofstaking pins, each pin extending through said die from said first endadjacent said flange at one of said pairs of spaced legs to a selecteddistance beyond said second surface, a ram spaced from said secondsurface of said die and a spring carried between said ram and die andengageable thereagainst said ram being movable to drive said die towardsaid retractor frame causing insertion of said spaced legs of the coverinto the openings in the side plate of the retractor frame, movement ofsaid ram to said second surface also driving said staking pins throughsaid radial flange to punch a portion of said flange to between saidlegs to hold them apart firmly within said openings.
 13. An apparatus inaccordance with claim 12 in which said spaced legs of said coverincludes radial shoulders to hook over the inside edge of the opening insaid side plate when said legs are inserted into said openings, saidlegs also having cam surfaces between the ends of said legs and saidshoulders to cam each pair of said resilient legs together for easierinsertion through said opening, said spring between said ram and saiddie being stiffer than the resistance presented by said spaced legsbeing cammed together for insertion into said opening, whereby movementof said ram toward said die first drives said spaced legs into saidopenings and upon continuous movement of said ram said ram engages saidstaking pins to drive them through said radial flange to force a plasticplug from said flange to between each pair said legs to prevent saidlegs from flexing together and said shoulders from disengaging.